This invention relates to antiperspirant formulations and more particularly to stable antiperspirant formulations containing improved emulsifying/suspending agents. 2. Description of the Related Art
Most common antiperspirant products are classified as either oil-in-water (o/w) emulsion systems or anhydrous suspension systems. Most antiperspirant emulsion systems contain effective amounts of nonionic emulsifying agents, about 20% active antiperspirant salt and as much as 70-75% water. Common consumer complaints associated with this type of antiperspirant product include excessive wetness and cooling effects upon application, long drying periods, and tackiness during dry-down and a white residue after application.
Anhydrous systems typically contain about 20% active antiperspirant salt about 10-20% other additives such as emollients, talc, etc., and as high as 60-70% volatile/non-volatile silicone fluids. These anhydrous products have improved application properties, velvety after-feel, etc., but are expensive due to their high content of silicone. Antiperspirant compositions adapted for roll-on-application are known and include such compositions as are described for example, in British patent application No. GB 2018590A. Such antiperspirant compositions are substantially anhydrous and comprise a powdered antiperspirant agent suspended by a traditional hydrophobic suspending agent, such as bentonite clay, in a liquid hydrophobic volatile silicone vehicle (generally 60 to 95% by weight). Additionally, such compositions, containing less than about 4% of other hydrophobic materials, such as emollients, are typically less volatile than the silicone fluids.
In addition, U.S. Pat. No. 4,268,499 describes antiperspirant emulsion compositions which comprise an aqueous solution of an astringent agent; a volatile, water-soluble liquid; a polydiorganosiloxane-polyoxyalkylene copolymer; an oil-in-water type surfactant; and a water-in-oil type surfactant. U.S Pat. No. 4,499,069 discloses antiperspirant emulsions which contain an antiperspirant salt of aluminum and/or zirconium, volatile cyclic silicone, water, and a low pH-stable emulsifier mixture of polyethylene glycol stearyl ether and a lipophilic co-emulsifier such that the HLB of the emulsifier mixture is more than 7.5 and less than 9.9.
Common suspending agents or rheological additives that have been used in roll-on anhydrous antiperspirant formulations include hydrophobic agents such as colloidal silica and montmorillonite clays. However, such hydrophobic agents require the use of polar additives, such as propylene carbonate, to render the suspending agent functional. Further, various disadvantages are associated with the use of montmorillonite clays in anhydrous antiperspirant formulations. Among these disadvantages are the requirements that high shear equipment be used during the antiperspirant preparation. Further, the resulting preparations still exhibit whitening on the user's skin and exhibit changes in viscosity over time.
Various phthalamate derivatives have been suggested as being useful in plant growth regulator formulations, insect repellent formulations, bactericidal, fungicidal and/or herbicidal formulations, additives for improving low temperature flow characteristics of petroleum distillate fuels, solvent extraction formulations for certain heavy metal ions, additives for thermal recording materials, thickeners for silicone grease and oil-based drilling muds, additives for water-insensitive coatings, plasticizers, etc. Phthalamic acids or phthalamate derivatives have also been used as additives for insecticidal compositions; additives for vulcanization activators; additives for rust and corrosion inhibitor formulations; additives for screen-clogging prevention and rust inhibition formulations; additives in catalyst systems for polyurethane foam formulations, etc.
Further, certain ammonium phthalamates have been used as additives in fuel oil compositions, blending agents for greases, lubricating oil additives, and thickening agents for lubricating oil compositions. These ammonium phthalamates have the general formula: ##STR2## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are C.sub.16 -C.sub.40, preferably C.sub.16 -C.sub.24 straight chain alkyl groups and may be the same or different.
Tallow is a fatty acid byproduct of the meat-packing industry obtained by rendering the body fat from cattle, horses and sheep. Tallows from different sources vary in free fatty acid content. The fatty acids normally found in tallow are various amounts of myristic acid, palmitic acid, stearic acid, oleic acid, and linoleic acid.
Several methods are known for the preparation of tallow amines, but a common method in industry is the conversion of a fatty acid to a nitrile by treatment with ammonia, followed by catalytic hydrogenation of the nitrile to primary, secondary, or tertiary amine by suitable adjustment in the reaction conditions. Tallow amines, as well as di(hydrogenated tallow) amine, are commercially available; for example, di(hydrogenated) tallow amines are available under the trade name ARMEEN.RTM. 2HT (Akzo Chemicals, Chicago, Ill.).
Various routes exist for the preparation of phthalamic acids and phthalamic acid salts. In U.S. Pat. No. 4,402,708, N,N-diarachidyl phthalamic acid was prepared by adding phthalic anhydride to a 40% solution of a fatty amine in toluene in a 1:1 mole ratio at 80.degree. C. The product was recovered by vacuum drying at 50.degree. C. 0.05 mmHg for 20.5 hours. It was reported that phthalic anhydride sublimation was observed.
U.S. Pat. No. 4,402,708 also describes a method for preparing N,N-dioctadecyl phthalamic acid dioctadecyl ammonium salt and N,N-diarachidyl phthalamic acid diarachidyl ammonium salt. Phthalic anhydride was added to a 10% solution of select fatty amines in toluene in an anhydride to amine mole ratio of 1:2. The product was recovered by filtering and film evaporating a 1:1 toluene/n-heptane solution at 55.degree. C., 40 mmHg.
Phthalamic acids have also been prepared by melting phthalic anhydride at about 131.degree. C. and subsequent addition of molten secondary amine. The reactants were added in an equimolar ratio. At the temperature used in this method, 131.degree. C. excessive phthalic anhydride sublimation occurs and increased product degradation was observed.
Phthalamic acids have also been prepared by addition of a solution of secondary fatty amines in isopropanol at about 78.degree. C. to a phthalic anhydride/isopropanol slurry in a 1:1 phthalic anhydride/amine molar ratio with subsequent vacuum stripping of the solvent. This method utilizes isopropanol as the solvent for the reaction. Isopropanol, a secondary alcohol, reacts with phthalic anhydride to yield the isopropyl mono ester of phthalic acid. At 78.degree. C., as much as 40% of the product may be an ester.
Attention is also directed to co-pending Goze et al. application 07/391,187, now abandoned and Goze et al. 07/542,780, now U.S. Pat. No. 5,015,415 both of which are incorporated herein by reference.